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ATEL # 1973; H.A. Krimm (CRESST/GSFC/USRA), J.A. Kennea (PSU), A.M. Levine (MIT)
on 16 Mar 2009; 23:32 UT
Password Certification: Hans A. Krimm (Hans.Krimm@nasa.gov)
Subjects: X-ray, Binaries, Pulsars, Transients
The hard X-ray transient pulsar and high-mass X-ray binary system Ginga 1843+009 was recently reported to be in outburst (Krimm et al, ATel #1959). Observations of this source were performed with the X-Ray Telescope (XRT) on Swift covering 2169 total seconds beginning at 2009-03-15 12:31:14 UT. The source was strongly detected in the XRT and the position was determined to be
RA(J2000) : 18h 45m 36s.9 (281.40372 deg)
Dec (J2000): +00d 51' 48".2 (+0.86338 deg)
with an estimated uncertainty of 1.5'' radius (90% confidence). This is 3.1 arc seconds from the X-ray position reported by the ROSAT/HRI (Dennerl & Greiner, IAUC 6645) and well within their reported 10" error radius. It is also 1.4 arc seconds from the optical counterpart reported by Israel et al, A&A 371, 1018 (2001) which confirms the optical identification.
The spectrum is best fit by an absorbed power law with parameters, Photon Index = 0.41 ± 0.01, n_H = 9.6 +/= 2.2 x 10^21 cm^-2. The flux in the 0.3-10 keV band is 4.5 ± 0.2 x 10^-10 erg/s/cm^2, which is ~5.2 x 10^-10 erg/s/cm^2 when corrected for absorption. The flux was steady over the duration of the observation.
In the Swift Burst Alert Telescope (BAT) energy range Ginga 1843+009 remains at a high flux level maintaining a daily average rate of 0.0223 ± 0.0014 ct/s/cm2 from 2009-03-12 through 2009-03-15 (MJD 54902-54905). There is a slight decrease in the source count rate for 2009-03-16. A fit to the BAT spectrum for the same time interval as the XRT observations yields a best fit to a power law spectrum with photon index 2.13 ± 0.26. The flux (15-150 keV) is 1.33 (+0.15,-0.76) X 10^-9 erg/s/cm^2 (red. chisq = 1.17 for 22 dof).
We thank Neil Gehrels and the Swift science operations team for approving and scheduling this Target of Opportunity observation.
Swift/BAT Transient Monitor light curves for Ginga 1843+009